Construction of exhaust passages of internal-combustion engines



Jan. 6, 1953 P. KOLLSMA N CONSTRUCTION OF EXHAUST PASSAGES OFINTERNAL-COMBUSTION ENGINES Filed July 10, 1946 3 Sheets-Sheet 2 TOPCENTER VALVE 3| cl. as

VALV E 47 m" BOTTOM CENTER INVENTOR PAUL KOLLSMAN aLZLIF LM-M 4.ATTORNEY Jan. 6, 1953 P. KOLLSMAN CONSTRUCTION EXHAUST SAGES OFINTERNAL- BUSTION INES Filed July 10, 1946 3 Sheets-Sheet 5 5W5 15 .JLf

INVENTOR PAUL KOLLSMAN M M M I; ATTCRNEY Patented Jan. 6, 1 953 UNITEDSTATES iPATENT OFFICE GONSTR-UGTION F EXHAUST PASSAGES' or-INTERNAL-COMBUSTIONENGINES3 Paul Kollsman, NewY-ork, N. Y.ApplicationJulylfl, 1946, Serial ,No. 6825664 4 Claims. (01. (SO-13)This invention provides; a method of,v and means for utilizing: the.energy of the. exhaust gases of internal combustion enginesv of thereciprocating type, and has particular application to aircraft engines.

According to the invention the. flow of combustion gases from therespective. combustion chambers or cylinders of aninternalc'ombustionengine is separated intoa flow of high velocityv and relatively highpressure for. conversioninto motive power and a separateflow of'relatively low velocity and lowipressure of the remainder of the gasesleaving the combustionchamber. The high pressure flow of gas maybeemployed: to produce reactive thrust'by discharge of the gas through anappropriate: reaction nozzle; The high pressure flow may also-be;used-:.to'drive aturbine rotor, for example the rotor ofa compresser.

According to the invention each combustion chamber, or cylinder, isprovided with-two separate discharge or exhaust passages, each passagebeing controlled bya separate exhaust valve. One of the passages isof'relatively narrow cross section, preferably'narrowerthan'the pas--sage provided by the respective exhaust valve when thevalve is open. Bysuch proportioning of the exhaust passage a sudden'an'd substantialpressure drop at the valveand a-corresponding energy loss is prevented.Atpoints-beyond the exhaust valve" the passage may diverge, graduallyincrease in: cross section, most advantageous-increase in velocity ofthe expanding high pressure flow ofgas. The :passage may lead to areactionnozzleforproducing a reactive thrust, or may lead toa'turbinenozzle for discharging the high velocity flow of combustion gasagainst the vanes or blades of a turbine rotor.

The second discharge passage is ofsubstantially larger cross section andserves'to remove substantially all of the'remainder ofthei cornbustiongases notflowing through the firstnamed passage to theatmosphere-orother point of combustion gas disposal.

The valves controlling adini-ssionof combustion gases to the firsthigh-Velocity passa'ge and the second law velocity passage are operatedin timed relationship with respect tothe movement of the pistonof therespective combustionchamber, and in suchmanner ,as 110, cause dischargef a p rtion f h o b tion asesuder hi h pressure through the highvelocity passage, while the second low velocitypassage is-= sti 1l,c-losed. After the peakpressure has been spent by I discharge of "anow of gas of'liigh velocity through to provide for a' 2: thehighvelocity passage, which flow is converted into motivepower ashereinbeiore mentioned, the secondexhaust valve opens and permitsremoval of substantially allo'f the remainingcom bustion gasesfrornfthe; combustion chamber through alpassa gej of low resistance. The firstdischarge valve controlling the high-velocity passage may be causedtoopenwhile the piston is still on its downwardcombustionstrohe; forexample approximately 59to before bottom center of the respectfve crank,and the second exhaustvalve controlling-the second discharge p ssa e mnen'ap r at v 0 2 fore bottom center;

While thetiming' of the opening of the two valves is important andshould occur successively as hereinbefore described, the two valves mayclose substantially simultaneously, for example when the respectivecrank-reaches top center.

The objects, features,,and advantages of this invention will appear morefully from the detailed description which follows accompanied bydrawings showing for the purposeof illustration devices for practicing"the invention.

The inventionalso consists in certain new and original features ofconstruction and combination of parts hereinafter set forth and claimed;

Although the characteristic features ofthe invention which are believed"to be novel will be particularly pointed out" in the'claims appendedhereto, the invention itself; its objects, and advantages, and themanner in which it maybe carriedout may be better understood byreferring to the following description taken in connection with theaccompanying drawings forming a part of it in which,

Figure 1 .is a side elevation, of a cylinder pist'on'and crankcombustion engine;

Figure 2 is a partial'view of a high velocity exhaust passage leadingfrom an engine of the type shown in Figure lto a turbine rotor;

Figure 3 is a detailed'view"illustrating, on an enlarged scale, the camsfor operating the two exhaust valves of the engine: shown in Fig. 1;

Figured is a diagramillustrating the timing of the two vexhaus'tvaliles;

Figure 5"is' a view of a modifiedforin of high velocity exhaust passage;

Figure '6 is asectional view through a high velocity exhaustpa's'sagehaving divergent walls automatically. adjustable, in dependence on thepressure of' the exhaust gases flowing through thepassage;

Figure 7" is a-sectiontaken on line l-l of Figififand. i H

partly. in section, of an internal Figure 8 is a perspective view of thepassage shown in Figs. 6 and '7.

In the following description and in the claims various details will beidentified by specific names for convenience. The names however areintended to be as generic in their application as the art will permit.In the drawings parts of the engine not necessary for an understandingof the invention are omitted for the sake of clarity.

Like reference characters refer to like parts in the several figures ofthe drawings.

In the drawings accompanying, and forming part of, this specificationcertain specific disclosureof the invention is made for the purpose ofexplanation of broader aspects of the invention, but it is understoodthat the details may be modified in various respects without departurefrom the principles of this invention, and that the invention may beapplied to and practiced by' other structures than the ones shown.

Referring to the drawings the engine shown in part in Figure 1 comprisesa cylinder housing I! having cooling fins I 2 and a flange :3 formounting on an engine housin (not shown).

A piston I4 is movable in the cylinder and forms with the cylinder acombustion chamber l5. The piston is pivotally attached to a connectingrod l6 by a pin [1, and the connecting rod it; engages a crank pin l8 ofa crank shaft [9.

Combustible mixture is admitted into the combustion chamber l5 throughan intake passage controlled by an intake valve 2|. The intake valve 2|has a stem 22 carrying a collar 23 against which a valve spring 24 bearstending to maintain the intake valve closed. The intake valve 2| isoperated by an intake valve lever 25 pivotally mounted at 26 andengaging with one end 27 the stem of the intake valve 2|. The other armof the intake valve lever 25 carries a roller 28 which engages theperiphery of a cam 29 on an intake cam shaft 30. The intake cam shaft 38is coupled to the crank shaft It in conventional manner (notillustrated) to cause the cam shaft 30 to turn at half the rate of thecrank shaft [9.

A first exhaust valve'3l controls the admission of combustion gas fromthe combustion chamber l5 to a relatively narrow discharge passage 32.The exhaust valve 3| has a stem 33 to which a collar 34 is attached. Avalve spring 35 bears against the collar 34 and tends to maintain theexhaust valve 3! closed. A first exhaust valve lever 36 pivotallymounted at 31 engages with one end 33 the valve stem 33 and carries atits other end a roller 39 engaging the periphery of a first exhaustvalve cam 49 on an exhaust valve cam shaft 4|.

A second exhaust valve cam 42 (Fig. l) is fixed on the same exhaustvalve cam shaft 4! and engages with its periphery a roller 43 at one endof a second exhaust valve lever 44. The second exhaust valve lever islikewise pivoted on the shaft 37 and engages with its other end 45 thestem 46 of a second exhaust valve 4'! controlling admission ofcombustion gas into a relatively wide exhaust passage 48.

The two cams and 42 are so arranged as to cause the first exhaust valve3| to open before the second exhaust valve 41 to permit the combustiongas of high pressure to pass through the relatively narrow first exhaustpassage 32. At the time of opening of the first exhaust valve 31 theases inside the combustion chamber l5 are at peak pressure. The asflowing through the exhaust passage 32 attains a very high velocity, upto sound velocity and even beyond the velocity of sound, depending onthe shape of the passage '4 32 and the pressure drop encountered by thegas during its flow through the passage.

After the peak pressure of the combustion gases is spent the second cam42 causes the second exhaust valve 41 to open, whereby substantially allof the remainder of the combustion gases, which now have dropped to arelatively low pressure, are permitted to escape from the combustionchamber I5 in preparation of the next suction and compression strokes ofthe engine.

The energy of the high pressure combustion gases may be utilized invarious ways.

The gases may be used to drive the rotor of a turbine. This is,illustrated in simplified manner in Figure 2 of the drawing. The exhaustvalve 3| controls the admission of combustion gases at peak pressureinto a relatively narrow discharge passage 32' leading to a dischargenozzle 49 directing a jet of gas against the vanes 50 of a turbine rotor5! on a rotor drive shaft 52. The passageis preferably narrower than thepassage provided by the exh ust valve 3! when the valve is open.

A second exhaust valve (not shown) is pro vided for opening and closinga second exhaust passage or exhaust stack 48 of relatively wide crosssection for the remova1 of'combustion gas still remaining in the.combustion chamber l5 after the gases of peak pressure have been removedthrough the first exhaust passage 32'.

A typical cam arrangement for the two exhaust valves is shown in Figurev3. The cams 4- and 42 are fixed on the same exhaust valve cam shaft 4|and move in the direction'of the arrow 53 at half the'rate'of'the enginecrank shaft. The elevated portion-of the two cameras are offset so as to"cause actuation of" the exhaust valve controlling the highpressureexhaust passage before actuation of the second exhaust valvewhich controls the exhaust passage of large diameter. In the illustratedembodiment the cams are offset 25 whichconsidering the ratio at whichthe cam shaft 4| 'is' geared'to the engine crankshaft, amounts to anadvance opening of the first exhaust valveove'r the second valve of 50in terms of engine crankshaft'movement.

A typical diagram illustrating the timing of two exhaust valves of anengine embodying the invention is shown in Figure 4. in terms ofcrankshaft movement. According to the illustrated arrangement exhaustvalve 3! opens approximately before bottom center. The exhaust valve 3!opens during the combustionstroke, at a time the piston is on its downward movement. When the exhaust valve 3! opens the mixture in thecombustion chamber of the engine was just fired by a spark plug orotherwise, is fully ignited and at high pressure forcing the pistondownwardly. While the pressure is still high the first exhaust valvebegins to open causing a flow of combustion gas of high pressure to passthrough the first; exhaust passage at great velocity. The energy of thiex haust gas is utilized either to produce a reactive thrust or to drivea suitable prime mover as here- 'inbefore described. Ten degrees beforebottom center of the crankshaft the valve 41 opens to permit theremainder of the combustion'gases to escape. Both valves remain openthroughout the upstroke of the piston and close at'top center of thecrankshaft when the suction stroke of the pistonis aboutto begin. I

It is evident that the'timing of the two valves relatively to each othermay be changedas well The diagram is as the opening and closing pointsof the valves withrespect to bottom and top center.

The exhaust passage for the high pressure gases may be made oisubstantia l-ly.- uniform cross section and of considerable length toproduce slugs of gas of considerable pressure whieh pa throughthepassage at highvelocity timed with the opening of the exhaust valve 3|.Asshown in Figure 5 the passage-32' isot uniform cross Section dpreferabl na rower th the D sage past the. valve 31'. The purpose ofmaking the us ass e 32" relat vel har sw i to make the pressure drop ator near the valvesmal l whereby energy losses at this point aremaintained correspondingly low.

Figures 6, 7 and 8 illustrate an exhaust passage 3'2" of graduallyincreasing cross section to permit flow velocities to in excess of thevelocity of sound. Two walls 54 and 55 of the passage 32 are adjustablein dependence on the changes in pressure of the exhaust gases flowingtherethrough. Flexible blades 56 and 51 of an alloy capable of resistinghigh temperatures are acted upon on the inside by the pressure of thegas flowing through the passage 32" and are acted upon on the other sideby the ambient pressure which may be the exhaust pressure of the turbinedriven by the exhaust gas, this pressure being near atmosphericpressure. Exhaust gases flowing through the passage 32" may attainvelocities in excess of the velocity of sound assuming the pressure dropof the gas is in excess of the so called critical drop. This pressureratio is measured at the intake point where the pressure of the gas is amaximum and the velocity substantially zero and at the discharge pointof the nozzle or passage 32" where the velocity is a maximum and theressure the lowest, for example substantially atmospheric pressure. Thecombustion gases are discharged at high velocity against the vanes 5!!of a turbine rotor 5| to drive the same.

The invention thus provides a method of and means for utilizing a greatpercentage of the energy of combustion gases of internal combustionengines which is ordinarily lost or wasted. The invention canconveniently be practiced with existing engines equipped with twoexhaust valves after appropriate modification of the engines to providefor actuation of the two exhaust valves one after the other and byproviding separate exhaust passages for the two valves.

While the invention has been explained and illustrated by application toan engine equipped with poppet valves it may also be practiced by orapplied to engines having sleeve valves. It is also applicable toengines of two cycle or two stroke type in which the piston acts as avalve member and controls appropriately located ports in the cylinderwall. Rearrangement of the ports or appropriate shaping of the edge ofthe piston controlling the ports manifestly produces the same results asthe valve mechanism of the illustrated four cycle engine. Thus variouschanges, additions, onfissions, substitutions and other modificationsmay be made, as will occur to persons skilled in the art withoutdeparture from the spirit and the teaching of this invention.

What is claimed is:

1. In a reciprocating internal combustion engine the combination with acylinder, of two distinct exhaust passages, namely a first high pressurepassage of relatively narrow cross section, and a second low pressureand low velocity passage of a cross section larger than said firstpassage; a poppet valve in each of said passages;

be obtained which are.

and means for Opening in. timed sequence first the valve in the highpressure passage and there,- aiter the valve in the low pressurepassage, the narrow high pressurepassagehaving a restricted portiondownstream ofits valve for maintenance of back pressure and a highvelocitynozzle portion downstream of said restricted; portion forconversion or pre s re secrets i i i kinetic energy, the high pressurepassage upstream of the restricted portion being so, dimensioned withrelation to its contro ling valve that its cross sectional area is atall pointsv less. than the valve opening considering the valvein fullyopeniposition, whereby turbulence losses, at the valve proper areminimized.

2. In an internal combustion engine the combination with a cylinder anda piston reciprocable therein, of, a first exhaust passage having atleast one movable wall acted upon by the pressure on the interior sideof the wall and by the pressure on the exterior side of said movablewall, respectively, the wall being unbiased and face to adjust itsposition in dependence on the difierence between said two pressuresacting on the wall to increase and decrease the angle of divergence ofsaid passage; stop means for limiting the extent to which the movablewall may be flexed to a pre-determined maximum angle of divergence ofthe nozzle passage toward the discharge end of the nozzle underpredominant gas pressure on said interior side; a first exhaust valvefor opening and closing said first passage; a second exhaust passage oflarger cross section than said first passage; a second exhaust valve foropening and closing said second passage; means timed with said pistonfor opening first said first valve and thereafter said second valve,whereby high and low pressure fiows of combustion gases are dischargedthrough said first and second passages, respectively; and a turbinerotor adapted to be acted upon by the gases discharged through saidfirst passage.

3. In an internal combustion engine the combination with a cylinder anda piston reciprocable therein, of an exhaust valve; an exhaust passageextending from said exhaust valve, said exhaust passage having a portionof narrowest cross-section less than the area of passage of said exhaustvalve when the valve is in fully open position, said exhaust passagefurther having a divergent portion including at least one adjustablewall adapted to increase and decrease by adjustment the degree ofdivergence of said passage portion; and means responsive to changes inpressure inside the passage for automatically adjusting said wall.

4. In an internal combustion engine the combination with a cylinder anda piston reciprocable therein, of a pair of exhaust valves, means foroperating said valves in timed sequence, separate exhaust passageextending from said valves, the passage extending from one valve havinga divergent portion bounded by fixed rigid walls, a flexible blade lyingadjacent one of said walls, said blade being secured to said one wall atone end near the valve and being free to move at the other end remotefrom the valve, said blade being acted upon by the gas pressure on theinterior side tending to flex the blade in a direction to increase thecross-sectional area of the nozzle if the gas pressure on the interiorside is greater than the pressure on the exterior side of the blade, therigid wall adjacent the blade limiting the extent to which the blade maybe flexed to a predetermined maximum angle of divergence Garve Feb. 194015 7 8 bf the nozzle passage towardsrthe dischargeend Number Name Dateof the flOZZlB. i 2,303,992 Frazer Dec. 1, 1942 i PAUL 2,342,262 FranzFeb. 22, 1944 REFERENCES CITED 5 FOREIGN PATENTS Th 1 11 f n' e r ofrecord in the Number' Country Date file 55,5313? ate? S a e r 179,925Great Britain May 10, 1923 1 r 1 522,935 Great'Britain July l, 1940 VUNITED STATES PATENTS 523,468 Great Britain July 15, 1940 Number NameDate 1,025,921 Muller 1 May 7, 1912 10 OTHER E E E 15 339,4 SimpsonMay.11, ,1920 The Internal Combustwn Engme.by D. R. 1 423 925 ThomasSept 12, 1922 Pye, published by Clarenden Press, Great Britain,2,051,436 Curtis Aug. 18, 1936 1931,page 1

